Mat

ABSTRACT

A mat with a textile surface ( 1 ) and an elastomer backing layer ( 2 ) that includes elastomer crumbs and a binder. The elastomer backing layer ( 2 ) includes voids between the elastomer crumbs for increased flexibility.

TECHNICAL FIELD

The present invention relates to a mat having a textile surface and anelastomer backing.

In particular, but not exclusively, the invention relates to a floormat. The invention also relates to other mats and mat-like products,including for example table mats and bar runners.

BACKGROUND TO THE INVENTION

Floor mats having a textile surface and a rubber backing are very wellknown and have been manufactured for many years. Typically, such matsinclude a tufted pile textile surface, for example of nylon, cotton,polypropylene or a mixture of such fibres, which is bonded to a rubberbacking sheet. Such mats are usually made by bonding the textile surfacelayer to a sheet of uncured rubber in a heated press. The heat from thepress vulcanises (cures) the rubber and at the same time bonds it to thetextile layer. A process for manufacturing such mats is described in EP0 367 441 A. Such mats have very good dust control characteristics, arehighly effective at removing dirt and moisture from the feet ofpedestrians, and have a good feel and appearance. The mats are alsowashable, extremely durable, highly flexible and lie flat on the floor.

Rubber backed floor mats with surfaces made of other textiles are alsoknown. These textiles may include knitted, woven, or non-woven fabrics(such as needle felts or spun-bonded fabrics), with or without a pile orraised nap, as well as flocked surfaces. The textile surface may bebonded under pressure to a rubber backing sheet, using a process similarto that described above. Other mats and mat-like products, such as tablemats and bar runners, have also been made in a similar fashion.

One disadvantage of the mats described above is that they tend to berather expensive, owing to the relatively high cost of the rubberbacking material. As a result, those mats have enjoyed only limitedcommercial success in certain market sectors, where a lower cost productis required. For example, in the commercial and retail or residentialmarket sectors, rubber backed dust control mats have achieved a marketpenetration of only about 5% of total mat sales, the remainder of thematting sold into this market sector being either unbacked or backedwith PVC or latex.

However, PVC and latex backed mats do have a number of disadvantages ascompared with conventional rubber backed mats. In particular, PVC backedmats have poor flexibility, especially at low temperatures, and afterbeing unrolled such mats often do not lie flat on the floor. They alsohave an inferior appearance and feel when compared with rubber backedmats, can become brittle with age, and can have poor resistance tomovement when placed on top of carpet. There are also growingenvironmental concerns associated with the manufacture and disposal ofPVC backed mats. These disadvantages have, however, been tolerated incertain market sectors, owing to the lower cost of the mats.

Recycled rubber has been used effectively at a low cost substitute forvirgin rubber in certain applications. Some examples of suchapplications are discussed below:

EP 0135595 describes a method for manufacturing a floor covering in theform of a web, which may be used as a sports surface. The web consistsof a lower textile base and an upper layer of disintegrated waste rubberand/or granules of new or scrap rubber that has been mixed with apre-polymer as a solvent-free single-component binder, spread on aconveyor belt, compressed and subsequently cured.

DE 4212757 describes a moulded component forming an elastic layer andcomprising a mixture of granulated recycled material and binders. Thecomponent has three compressed layers of uniform thickness bondedtogether at their interfaces. Upper and middle layers are formed by flatplates and the lower layer has hump-shaped feet separated by grooves.The individual layers are formed in different materials with differentparticle sizes. The component can be used as a covering, for example forfloors.

A mat with a compression moulded rubber crumb backing and having a flocksurface applied to the backing is available under the brand name “Royalmat”. The compression moulded backing is made by mixing rubber crumbwith a binder and then compressing a layer of the mixture in a mould ata high pressure while the binder bonds the crumbs together. The flockedtextile surface is subsequently applied to the backing using anadhesive.

Compression moulding produces a rubber crumb backing that has a highdensity and low deformability. This makes the mat heavy and inflexible,with the result that it does not conform well to the shape of the floorbeneath it. The mat does not therefore have the performancecharacteristics of a conventional rubber backed mat.

Rubber carpet underlay manufactured from lightly bonded crumb rubber isalso known. The underlay is however made without any significantpressure and as a result it is not sufficiently well bonded to make itdurable enough for use as a mat backing.

Notwithstanding the aforesaid applications, recycled rubber does nothave the same performance characteristics as virgin rubber. Inparticular, it has a lower tear resistance and a higher stiffness, owingto the presence of a binder material. As a result, recycled rubber hasnot generally been thought suitable for use as the backing material fora mat, since it has been thought to offer no significant advantages overPVC.

It is therefore desirable to provide a mat that overcomes theperformance shortcomings of PVC backed mats and compression mouldedmats, and that avoids the relatively high cost associated withconventional rubber-backed mats.

DISCLOSURE OF THE INVENTION

According to one aspect of the present invention there is provided a matwith a textile surface and an elastomer backing that includes elastomercrumbs and a binder, characterised in that the elastomer backingincludes voids between the elastomer crumbs.

Throughout this specification the term “crumb” has the normal meaning inthe rubber industry of any “broken down” rubber: thus, a crumb of rubbercan be any size in a range that includes powder, granules and chips. Theterm “powder” means crumb that will pass a 2 mm mesh or crumb with amaximum dimension of 2 mm as the context requires. “Granule” means crumbthat will pass a 6 mm mesh or crumb with a maximum dimension of 6 mm, asthe context requires. Granules may include some powder but are generallylarger than powder and have a weight average size that is near to themaximum of the size specification for the granule. “Chips” means crumbsthat are larger than granules.

It should be noted that any batch of rubber crumb normally contains aproportion of crumbs smaller than the nominal crumb size. Thus, forexample, we found that crumb made using a granulator with a 1.5 mmscreen (i.e. having holes of diameter 1.5 mm) had a distribution ofcrumb sizes, measured by using standard “Endecott” test sieves(IS03310-1:2200, BE410-1:2000, ASTM E11:95), comprising by weight 72.82%in the range 1.0-2.0 mm, 17.45% of 0.71-1.0 mm, 6.90% of 0.5-0.71 mm,2.65% of 0.25-0.5 mm and 0.18% of 0-0.25 mm. Therefore, in the presentspecification, where we refer to 1.5 mm crumb, we mean crumb made usinga granulator with a 1.5 mm screen.

We have found, surprisingly, that it is possible to make a mat havingsuperior performance characteristics with a backing made of elastomercrumb and a binder. In particular, we have found that by carefullycontrolling the pressure in the production process, we can produce a matwith voids between the elastomer crumbs in the backing, which meets orexceeds the performance of mats with a PVC backing layer and existingcompression moulded mats. The mat can be produced in a single process,using relatively inexpensive materials (for example, recycled rubberfrom old mats), and therefore provides a high performance but low costalternative to conventional rubber-backed mats, compression moulded matsand PVC mats.

The presence of voids between the crumbs increases the flexibility ofthe backing, thereby compensating for the stiffening effect of thebinder and providing a deformability that is comparable to that of aconventional rubber backing. The mat is more flexible than bothcompression moulded rubber backed mats and PVC backed mats, in thelatter case particularly at low temperatures. The tear strength of thebacking is however much greater than that of granulated rubber carpetunderlay, and is adequate for most mat backings, even in unsupportedborder regions of the mat. The backing is also extremely stable whenplaced on top of carpet, probably because the pile fibres of the carpetare gripped in the numerous small gaps between the crumbs of thebacking. It is also relatively light and it has good fire resistancecompared to a conventional rubber backed mat.

The elastomer is preferably rubber, and more preferably nitrile rubber.This backing material provides better performance than PVC at a costthat may be less than PVC and without the environmental concernsassociated with PVC. Nitrile rubber is a term used to describe acompounded rubber mixture of which the main polymeric content is anacrylonitrile butadiene copolymer. It may also contain fillers such ascarbon black, a curing system, plasticisers and other ancillarycomponents. This backing material provides better performance than PVCat a cost that may be less than PVC and without the environmentalconcerns associated with PVC.

Advantageously, the elastomer crumb backing exhibits a deformabilityfrom at least 14% as measured by the test herein defined. Preferably thedeformability is 14 to 50%, more preferably 14 to 25%.

Advantageously, the elastomer backing has a bulk density in the range 45to 70%, preferably 55 to 70%, of the elastomer from which the crumbs aremade.

Advantageously, the backing has a density of less than 1 g/cm³. Thebacking preferably has a density in the range 0.5 to 0.9 g/cm³, morepreferably 0.7 to 0.9 g/cm³.

Advantageously, the backing exhibits a tear resistance strength of atleast 0.8N/mm². Preferably the tear resistance strength is about1.5N/mm² or higher.

The mat backing preferably has a thickness of a least 1 mm. The crumbsize preferably may be within the range of about 0.8 mm to about 6 mm,with crumb sizes less than about 5 mm diameter being generallypreferred. More specifically, crumb sizes within the range of about 2 mmto about 4 mm, and preferably sizes of about 3 mm or less, have beenfound to be particularly advantageous for use. The choice of crumb sizeto be used, and the relative percentage of powder used, if any, dependssomewhat upon the desired performance aspects of the mat and the desiredmanufacturing cost. Because use of small crumb (say, for example, powderless than about 1 mm) tends to require increased use of binder andthereby increased manufacturing cost, limiting use of crumb to smallgranules and large powder (e.g., crumb within the range of about 1 mm toabout 4 mm, or, preferably, predominantly crumb within the range ofabout 2 mm to about 3 mm) may be preferred if minimizing manufacturingcost is important.

The use of powdered crumb increases the strength of the resultingbacking, and generates a smoother appearance, but increases the cost ofproduction, both in the need for additional grinding and in the need forthe use of additional binder. Accordingly, the amount of powdered crumbcan be adjusted to suit the needs of the product; typically, includingpowder of at least 10% by weight has been used. The elastomer crumb ispreferably at least partially comprised of crumbed vulcanised rubber.The rubber is preferably nitrile rubber. The elastomer crumb may includea combination of crumb sizes in addition to the powdered elastomercrumb.

The binder may be comprised of any of several different materials. Forexample, the binder may be a polyurethane MDI binder. Preferably it isselected from the group consisting of 4,4-methylene di-p-phenyleneisocyanate (MDI) polyurethane one- and two-component adhesives.Advantageously the binder is a solvent-free, one component (moisturecuring) polyurethane adhesive. Such binder may typically be present at alevel of from 4 to 12%. Alternatively the binder may be a hot meltbinder and is desirably present at a level of from 3 to 10%. Whenpowdered elastomer crumb is included in the backing and the binder is aone component polyurethane adhesive, the binder level preferably lies inthe range 9 to 20%, as may be determined by experimentation.Exceptionally, binder levels of up to 25% may be employed.

The backing may include powdered or liquid additives selected from thegroup consisting of: anti-microbial additives, anti-flammabilityadditives, pigments, such as iron oxide, and anti-static additives, suchas carbon fibres. This provides added functionality to the mat.

Advantageously, a crumb rubber border extending beyond the periphery ofthe textile surface is provided on at least two opposite edges of themat. The crumb rubber border may be provided around the entire peripheryof the mat.

Advantageously, the textile surface comprises a tufted pile textile,including tufts of yarn tufted into a tufting substrate. Alternatively,the textile surface comprises a knitted, woven or non-woven textile, ora flock surface.

An edging strip may be bonded to the elastomer backing adjacent at leastone edge thereof. Advantageously, the textile surface element partiallyoverlaps and is bonded to the edging strip.

The mat may be a floor mat, a table mat, a bar runner or any other mator mat-like product.

Often, commercial or retail floor mats are backed with PVC. Theadvantage of this mat backed with elastomer crumb is that it is similarin cost of production to PVC and has superior appearance and feel toPVC. Furthermore, it has much better low temperature flexibility thanPVC, which means that the elastomer crumb backed mat lies better on thefloor than a PVC backed mat. The mat is also less liable to becomebrittle with age than a PVC backed mat. In tests, we found that crumbrubber backed mats remained sufficiently flexible to unroll and lie flatimmediately after being removed from storage at minus 16° C. Matsaccording to the invention also unroll more easily than PVC mats athigher temperatures and tend to give off less of a distinctive odour ofrubber than conventional vulcanised rubber mats. The ability to roll upis very important for commercial mats as they are often over 6 m longand can be as long as 25 m. It is also important for retail mats as theyare frequently sold in rolled up form to enable the larger sizes to becarried home. The lie flatness or amount of rippling of the mat edgesafter both mats had been rolled up was visibly superior in the mataccording to the invention.

The invention will now be further described by way of example only andwith reference to the drawings, which are briefly described as follows:

FIG. 1 is a cross-sectional side elevation of a mat;

FIG. 2 is a top plan view of the mat;

FIG. 3 is an enlarged partial bottom view of the mat;

FIG. 4 is a side elevation of a press for manufacturing the mat;

FIGS. 5A to 5D are photographs showing in cross-section the structure ofvarious rubber crumb backing layers;

FIG. 6 is an exploded side view of a laid-up mat assembly, prior topressing, according to a second embodiment of the invention, and

FIG. 7 is an enlarged partial cross-sectional side elevation of a mataccording to the second embodiment of the invention.

With reference to FIGS. 1 and 2, a mat is shown with a textile surface 1bonded to a nitrile rubber crumb backing 2. In this case, the textilesurface is shown as a tufted pile textile. It should be understoodhowever that other textiles may also be used including, for example,knitted, woven and non-woven fabrics, as well as flocked surfaces.

The textile surface 1 includes a tufted pile, which is tufted onto asubstrate (or primary backing), for example of woven or non-wovenpolyester or polypropylene. The tufted pile can be cut, looped or both,and typically consists of cut pile. Suitable textile materials includepolypropylene, nylon, cotton, blends thereof and any other fibres oryarns that can be tufted into a tufting substrate to form a pilesurface. The yarn may be solution dyed or the mats may be printed duringor after manufacture.

The textile surface 1 is slightly smaller than the backing, leaving arubber crumb border 3 that extends around the periphery of the mat.Alternatively, the border strips may be omitted entirely or two borderstrips may be provided on opposite sides of the mat, with no borders atthe ends of the mat. This latter construction is preferred for rolls ormatting. The width of the mat and the other dimensions may be any ofthose conventionally used for commercial or retail mats or any othersuitable dimensions. For mats with a low backing thickness, it isadvantageous for the textile surface to cover the whole upper surface ofthe backing. For aesthetic reasons, such mats are often provided withwhat is termed an “optical border”, which is a dark printed area aroundthe periphery of the mat.

FIG. 3 shows the rubber crumb backing 2 in more detail. It generallycomprises a series of rubber crumbs 6 bonded together with a binder (notshown), which bonds each crumb to the adjacent crumbs. The binder alsobonds the backing 2 to the textile surface 1. A plurality of voids 7exist between the rubber crumbs, some of which may be partially or fullyfilled with the binder. Owing to the presence of the voids, the bulkdensity of the backing layer is less than the density of the solidrubber material of which the crumbs are composed, and is typically about45%-70% of the solid rubber density.

Generally, any batch of granules will include a distribution of granulesizes, the average granule size being significantly less than themaximum that will pass through the mesh. For example, we have found whenusing a 4 mm mesh that the majority of the granules lie in the range 1to 3 mm (i.e. they will pass through a 3 mm mesh but not a 1 mm mesh).Further, it should be noted that the granules tend to be irregular inshape and often have a thickness that is considerably less than thenominal granule size. Thus, with the compaction that occurs during thepressing process, we have found that a backing layer can be made usinggranules having a nominal size larger than the thickness of the backinglayer.

The crumb is preferably nitrile rubber, and is preferably rubber fromrecycled industrial mats. The rental industrial segment is an idealsource of raw material for the crumb because it ensures that low bleed,low staining nitrile rubber crumb is used as the starting point for theproduction of the mats of the invention. The crumb may include someflock from the textile surface of the original mat, perhaps in bondingrelationship to the crumb. The flock content should preferably be as lowas possible, most preferably less than 10% by weight.

The crumb size may range from about 0.01 to 8 mm. Generally, the size isselected to be as large as possible for the use and properties required.However, crumb larger than granules (i.e. larger than about 6 mm) may beregarded as excessively granular, and crumb that is smaller than about0.8 mm may be regarded as excessively costly (both in terms of supplyand increased binder requirements). Generally, it has been found thatcrumb within the range of about 2 mm to about 4 mm is preferred.Specifically, crumb that passes a 4 mm aperture screen (i.e. crumbpredominantly of about 3 mm or less) has been found to be particularlyuseful for floor mats. In accordance with the teachings herein, powder(i.e. crumb less than 2 mm in size) may be used as desired. Crumb sizecan be chosen to give different amounts of resilience in the mat. Wehave found that larger crumbs provide greater resilience.

Crumb may be mixed with powder of the same material or a differentmaterial to provide a greater tear resistance. We have found that thepowder increases the tensile strength for a given binder level. The useof other additives in powdered or liquid form may provide the same ordifferent advantages. Suitable additives include, but are not limitedto, anti-microbial materials, anti-flammability additives, odorants,colorants or pigments such as iron oxide powder, anti-static additivessuch as carbon fibres, fillers and other generally known additives.

The binder may be either a heat setting or thermoplastic type. Dependingon the process utilized to manufacture the backing, the binder can be inliquid or powder form. Preferably, the binder is selected from one ofthe following types: polyurethane reactive hotmelts, copolyester orcopolyamide reactive and thermoplastic hotmelts, 4,4-methylenedi-p-phenylene isocyanate (MDI) polyurethane one- and two-componentadhesives.

It is important that the binder has good adhesive properties to ensurethat the crumb is well bound, and that sufficient free binder isprovided to be capable of forming a physical or chemical bond to thetextile surface. The binder should also exhibit sufficient cohesivestrength to give the backing sufficient strength. When a tufted piletextile is used, the binder should be one that cures or sets at asufficiently low temperature and pressure that pile crush issubstantially avoided.

The binder may contain any of the known cross linkers or curingaccelerators to suit the process and the desired properties of the matbeing manufactured and the rubber being used.

The binder performs the dual function of holding together the crumb toform a backing and bonding the backing to the textile surface of themat. To perform both functions adequately we have found that binderlevels should be in the range 2 to 12% by weight of the crumbs whenchips or granules are used. Use of less than 2% binder gives a very poortensile strength in the backing. Use of greater than 12% gives a stiffbacking and causes a skin to form. When rubber crumb powder is added tothe backing, the amount of binder needed for optimal properties isgreater due to the higher surface area of the rubber crumb powder on aweight for weight basis. For powders, especially finer rubber crumbpowders of size less than 0.5 mm, the quantity of binder should lie inthe range 9 to 20%, depending upon the size and quantity of the powderadded. Because the powder addition increases the tensile strength,inclusion of a little powder can improve the strength of the backingwithout increasing the binder content excessively.

Generally, there is an inverse relationship between the binder contentand size of the rubber crumb, and between the binder content andpressure applied to the rubber crumb while forming the backing layer.Therefore, as the crumb size and the pressure increase, the bindercontent decreases. The binder content also depends on other factors,such as the type of binder, the rubber material used and the type offabric, and can be determined by routine experimentation.

For example, the binder may be a liquid polyurethane MDI binder, inwhich case it is preferably present at a level of from 4 to 12% if thebacking consists primarily of chips or granules. The binder may containfurther additives that are in liquid form and are compatible with thebinder, such as colorants, plasticisers and perfumes. The binder mayalso contain other additives, such as those listed as crumb additives,provided that they are suitable for addition in a liquid medium.

The binder may alternatively be a thermoplastic or thermosetting hotmelt powder, in which case it is preferably present at a level from 3 to10% if the backing consists primarily of chips or granules. A powderedbinder may also contain other additives such as those listed as crumbadditives, provided that they are suitable for addition in a powdermedium.

The preferred ranges for binder content may thus be summarized asfollows:

Backing of chips/granules: binder content in range 2 to 12%, preferably4 to 12% with an MDI binder or 3 to 10% with a hot melt binder.

Backing with ≧10% powder: binder content in range 9 to 20%, preferably14% or more.

Exceptionally, a binder content of up to 25% may be employed, eventhough this may lead to the formation of a skin.

Examples of mat products according to the invention are given inTable 1. TABLE 1 Example Products Floor mat - tufted Floor mat - tuftednylon on rubber Bar runner - Poster mat - polypropylene granule backingknitted polyester woven polyester fabric on rubber with printed opticalfabric on rubber on rubber granule Property powder backing borderspowder backing backing Textile Type Polypropylene Nylon 6 PolyesterPolyester Weight  500 gm⁻²  600 gm⁻²  237 gm⁻²  200 gm⁻² Method TuftedTufted Knitted Woven Tufting substrate  80 gm⁻² Polyback  140 gm⁻²Colback n/a n/a Backing Material   0.8 mm powder   3 mm granule   0.5 mmpowder   4 mm granule (screen size) Thickness   1.5 mm   4.0 mm   1.0 mm  1.5 mm Weight 2000 gm⁻² 3000 gm⁻² 1333 gm⁻² 2000 gm⁻² Total Weight2580 gm⁻² 3740 gm⁻² 1570 gm⁻² 2200 gm⁻² Borders  15 mm None None Nonegm⁻² is grams per square meter

A process for making the mat of FIGS. 1-3 will now be described withreference to FIG. 4, which is a schematic exploded cross-section of amat as laid up in a press during manufacture. The press 9 includes aheated metal platen 10, above which there is an inflatable diaphragm 12,mounted on a frame 14. The frame 14 may be either fixed or moveable,depending on whether the press has a fixed or variable opening aperture.A conveyor belt 16 made, for example, of PTFE-coated woven glass fabricextends around and beyond the heated platen 10, allowing laid up mats tobe transferred in and out of the press 9.

The lay up consists of the following items placed in order on theconveyor belt 16. First, a mixture of rubber crumb, binder and any otherrequired additives is made up and spread evenly onto the conveyor belt16, forming a loose crumb layer 18 having a thickness, a width and alength that are slightly greater than the required dimensions of thefinished backing layer 2. The binder may, for example, be a hot meltpowder, in which case the amount of binder typically varies between 3%and 10% by weight, depending on the size of the crumbs and the amountand type of any optional additives.

A die cut fabric layer 20, for example of tufted pile textile on asuitable substrate, is placed on top of the loose crumb layer 18; thelength and width of the fabric layer preferably should be slightly lessthan the equivalent dimensions of the loose crumb layer if a rubberborder is required. The laid up mat is then covered with a release sheet22 of PTFE-coated woven glass fabric, to prevent the rubber backingsheet 2 sticking to the diaphragm 12.

The press is heated to a temperature of about 125° C. The conveyor belt16 is advanced to position the laid up mat between the platen 10 and thediaphragm 12, and the diaphragm 12 is then inflated, for example, to apressure of about 4 pounds per square inch, to press the laid up matagainst the heated platen 10, typically for a cycle time of 10 minutes.

The heat from the platen 10 activates the binder, thereby binding therubber crumbs together and forming the backing layer 2. At the sametime, the pressure from the diaphragm 12 slightly compresses the backinglayer 2 to ensure a good bond between the granules, and presses thefabric layer 1 against the backing layer 2, allowing the binder to bondthe two layers together.

After completion of the pressing process, the diaphragm 12 is deflatedand the rubber backed mat is removed from the press 9 and allowed tocool. The release sheet 22 is then removed and, if necessary, the edgesof the rubber backing layer 2 are trimmed, for example using anysuitable knife or other cutting means, for example, a guillotine.

We have found that by using the process described above, we can controlthe flexibility and strength of the backing by adjusting the pressureapplied to the backing in the press. By increasing the pressure thetensile strength of the backing can be increased, and by reducing thepressure the flexibility of the backing can be increased. The desiredperformance characteristics of the backing can thus be achieved bycareful control of the backing pressure.

Also, when tufted pile textiles are used, the problem of pile crush canbe substantially avoided. This is because the press operates at a muchlower pressure (typically, 4 psig) and temperature (about 125° C.) thanis usual in a conventional mat press, which typically operates at apressure of 20 to 40 psig or higher and at temperatures above 160° C. Itmay be possible to operate the press at even lower temperature (forexample down to about 50° C.) by the use of suitable binders. The lowerpressure and temperature are possible because the rubber crumb isalready vulcanised and the heat and pressure only have to be sufficientto activate the binder and press the granules together so that they bondto one another and to the fabric layer. In a conventional mat makingprocess, a much higher pressure and temperature is required to softenand cure the vulcanised rubber backing, and to press the fabric layerinto the backing.

The mats provide a higher level of comfort and are less dense thancompression moulded mats, which have high-density backings. Theinventive mat is suited to the retail and commercial segments.

EXAMPLE

A batch of 0.8 to 3 mm rubber crumb was made up by granulatingvulcanised nitrile rubber in a granulator with a 3 mm screen and thenpassing the granules over a 0.8 mm screen to remove fines smaller than0.8 mm. The granules were then mixed with 8% MDI binder. The mixture wasdivided up and sample rubber mat backings were made by spreading thecrumb mixture evenly with a thickness of 8 mm and then pressing themixture using an air bag press at various pressures to produce a seriesof samples. The pressure ranged from no pressure in the air bag throughto 45 psig. All the rubber backing samples so formed were set or pressedat 125° C. for 10 minutes. A 25 mm square section was then cut from eachsample and its thickness and weight were measured. From this, thedensity of the sample and the bulk density of the rubber crumb layer wasdetermined, expressed as a percentage of the density of the materialfrom which the crumb was made. The data are given in Table 2. TABLE 2Density Test Data Pres- Thick- Thick- Bulk sure ness ness Weight VolumeDensity density Sample psig mm % g cm³ g/cm³ % A 0 8.1 100 2.8 5.06 0.5545 B 2 6.2 78 2.8 3.87 0.72 59 C 4 5.4 68 2.6 3.37 0.77 63 D 8 5.4 682.9 3.37 0.86 70 E 16 5.0 63 3.2 3.12 1.02 84 F 32 4.3 54 2.8 2.68 1.0485 G 45 3.9 49 2.7 2.43 1.11 91 Royal 7.3 5.0 4.56 1.10 90 Rubber 1.22100

The sample referred to as “Royal”is the backing layer of the prior art“Royal” mat referred to previously, which is formed by compressionmoulding rubber crumb in a fixed platen press to form a very densebacking. The sample referred to as “Rubber” is a solid vulcanised rubberbacking of a conventional floor mat.

It can be seen from Table 2 that the density increases as the pressureapplied increases. The maximum density achieved was 1.11 g/cm³,equivalent to a bulk density that is 91% of the density of the solidrubber backing. Theoretically, if the backing sample were 100%compressed to remove all voids the density would be about 1.22 g/cm³ tomatch that of the solid rubber backing of the conventional vulcanisedmat referred to as “Rubber”. From the table, it can be seen that thedensity of the compression moulded product (the “Royal” mat) is aboutthe same as the density we obtained using a 45 psi pressure.

Table 2 also gives a general view of the backing thickness reductionfrom around 8 mm before to around 4-6 mm after pressing, representing areduction of up to 50% of its original thickness.

The samples were then tested to determine their deformability. This testwas done with a thickness gauge with a 10 mm diameter foot. Weight wasapplied to the measuring plunger of the thickness gauge. First the newbacking thickness was measured with 60 g weight and then the thicknesswas re-measured with a 800 g weight. The deformability is the percentagefall in the thickness at 60 g loading when the loading pressure wasincreased to 800 g. The results are shown in Table 3. TABLE 3Deformability Test Data Sample ID Pressure 60 g 800 g Deformability % A0 7.65 4.0 47.7 B 2 5.70 4.3 24.6 C 4 5.10 4.2 17.6 D 8 5.30 4.55 14.2 E16 4.80 4.3 10.4 F 32 4.15 3.75 9.6 G 45 3.70 3.5 5.4 Royal 7.45 7.055.4 Rubber 6.10 5.6 8.2

From Table 2 it can be seen that there is a correlation betweenformation pressure and density, and from Table 3 it can be seen thatthere is a correlation between pressure (density) and deformability.This correlation may be expressed as follows: the higher the formationpressure, the higher the density, and the higher the density, the lowerthe deformability.

In Tables 2, 3 and 4, the sample referred to as “Rubber” is acommercially available vulcanised rubber backed industrial mat. Thevulcanised rubber is softer and therefore more deformable than the highpressure crumb backings because of the presence of binder in the latter.The binder material is relatively hard, compared with vulcanised rubber,and this reduces the flexibility of the backing.

In the mat made by compression moulding (the “Royal” mat), the bulkdensity of the mat backing was about 90% of the density of the materialfrom which the crumb was made and is usually in the range of 80-95%. Thebacking is harder than the material from which the crumb was madebecause of the presence of the binder.

On the other hand, using the process according to the invention, thebulk density of the backing can be varied to lie within 45-90% of thedensity of the material from which the crumb was made. Preferably, thebulk density of the backing is made to lie within 45-70%, and morepreferably within 55-70%, of the density of the crumb material. Thisprovides a backing with a deformability of about 14-50%, more preferably14-25%, which is better than that of a compression moulded mat andcomparable to that of a conventional rubber backed mat. The inventionalso offers the advantage of a lighter weight mat that is more easilywashed and dried and easier to carry and transport, whilst still being arubber backed mat. This also has the advantage that the product densitycan be varied by a minor process change to enable productionflexibility. Additives could also be included in the crumb and bindermix to further control or change the density if required.

The effect of different formation pressures on the structure of thebacking layer is shown photographically in FIGS. 5A to 5D. FIG. 5A showsa cross-section at a magnification of about 10× through a backing layermade up from 1.5 mm rubber granules together with 8% MDI binder and 5%yellow oxide (which was added to binder to improve its visibility), andpressed at a pressure of 2 PSI. Some of the granules were coloured blueand others were coloured black, to allow the boundaries between thegranules to be seen more easily (the blue granules appear a lightershade of grey). The individual granules can be easily identified and aresubstantially undeformed, having straight edges and sharp corners. Thegranules are packed together as a loose conglomeration giving thebacking a sponge-like appearance. Many voids can be seen between thegranules, those voids being generally only partially filled with binder.

FIG. 5B shows a similar backing, produced at a pressure of 10 PSI. Thebacking has a tighter, more compact structure and some slightdeformation of the granules can be seen. This increases the area ofcontact between adjacent granules and increases the tear strength of thebacking. Nevertheless, many voids are still visible between thegranules, which are only partially filled with binder.

FIG. 5C shows a backing made using the same mixture of granules andbinder, but using a compression moulding process in a 20 tonne press. Inthis case, severe deformation of the granules has taken place and theboundaries between adjacent granules are almost unidentifiable, exceptwhere the granules have different colours. The backing layer is denseand virtually solid, with hardly any voids between the granules.

FIG. 5D shows a cross-section through a conventional compression mouldedmat (the prior art “Royal” mat). As with the backing layer shown in FIG.5C, the boundaries between adjacent granules are almost unidentifiableand the backing layer is dense and solid, with hardly any voids (exceptwhere the backing layer has fractured).

Tear Strength Test

To test the strength of the granulated rubber backing, a batch ofsamples was made up using different formation pressures, ranging from nopressure in the air bag through to 8 psig. All the rubber backingsamples so formed were set or pressed at 125° C. for 10 minutes. Sixtest pieces were then cut from each sample and the tear strength of eachtest piece was measured, with three measurements being made in each oftwo orthogonal directions. The results are shown in Table 4. TABLE 4Tear Strength Test Data Tear Strength - Tear Strength - AverageFormation Direction 1 N/mm² Direction 2 N/mm² tear Pressure Test Teststrength PSI 1 Test 2 Test 3 4 Test 5 Test 6 N/mm² 0 0.09 0.11 0.06 0.080.06 0.08 0.08 2 0.89 0.88 0.95 0.82 0.98 0.81 0.89 4 1.59 1.56 1.511.48 1.45 1.48 1.51 8 1.41 1.55 1.57 1.52 1.55 1.48 1.51

Table 4 shows that there is a correlation between formation pressure andtear strength, the strength increasing rapidly up to a formationpressure of about 4 PSI, but with no significant additional increase instrength at higher formation pressures. We have found that a tearstrength of about 0.8N/mm² or higher is quite adequate for many matapplications, even though this is considerably less than the tearstrength of a conventional solid rubber mat backing.

Pile Crush Test

For this test, we made a number of mat samples, each including a tuftedpile surface and a rubber crumb backing made using the same pressingtemperature, time and pressure values as set out in Table 2. The extentof pile crush and the commercial acceptable of the different mat sampleswere then assessed subjectively. We found that for pressures of about 8psig and lower, pile crush was relatively minor and the product wascommercially acceptable. However, at pressures above about 8 psig,significant pile crush occurred and the product was consideredcommercially unacceptable without subsequently being laundered orprocessed in some other way to raise the pile. The preferred tufted pilemats are therefore those manufactured at a pressure of about 8 psig orless, which have backings with a bulk density in the range 45-70% of thedensity of the solid rubber material from which the rubber crumb isderived. The best mats were those manufactured at pressures of 2-8 psig,which have a bulk density in the range of about 55-70%.

Low Temperature Recovery Test.

For this test a 300 mm×200 mm sample of each product to be tested wasconditioned at a room temperature of 22° C. for 2 hours and then rolledlengthwise around a 40 mm diameter tube and secured with a cable tie.The samples were then placed in a freezer and kept at a temperature of−16° C. for 24 hours. The samples were removed from the freezer, thecable tie was cut and the samples were then left at 22° C. for 10minutes to relax on a flat, wood surface. Measurements were then made ofthe height, if any, of the ends of the mat samples above the flatsurface due to the curl of the sample. Repeat measurements were made at20 minutes and 60 minutes following removal from the freezer.

Table 5 shows the results of the above test when comparing: aconventionally backed nitrite rubber mat (A), a commercially availablemat backed with PVC (B), a prior art rubber crumb backed mat formed bycompression moulding in a fixed platen press to form a very densebacking (the “Royal” mat), and a mat according to the invention backedwith granulated nitrite rubber crumb (D). TABLE 5 Prior art matsInventive mat A: Regular B: PVC D: Rubber rubber backed C: Compressioncrumb Time backed mat mat moulded mat backed mat +10 minutes Flat (0 mm)37 mm  50 mm  10 mm +20 minutes Flat (0 mm) 7 mm 6 mm Flat (0 mm) +60minutes Flat (0 mm) 2 mm 2 mm Flat (0 mm)

The mat according to the invention outperforms both the PVC backed matand the compression moulded rubber crumb mat and it is not significantlydifferent in performance from a high specification conventional rubberbacked mat.

Sand Retention Test.

For this test two equal size samples of a mat (0.05781 m²) were cut out.Each sample was weighed. They were then fixed to the inside of atetrapod chamber. A tetrapod is a known piece of testing equipment usedto measure wear of carpeting and the like. 1000 g of dry sand with aparticle size distribution as shown in Table 6 was added along with fivegolf balls to provide agitation. TABLE 6 Particle size mm Weight %0.00-0.25 7.0 0.25-0.50 71.0 0.50-0.71 15.7 0.71-1.00 3.5 1.00-2.00 1.72.00-2.80 0.16 2.80-4.00 0.02 4.00-6.70 0 6.70 and above 0

The chamber was then sealed to prevent either the golf balls or the sandleaking out during the test and it was set revolving for 1000revolutions. On completion of the test, each sample was removed and theweight increase of the sample recorded. The amount of sand retained ineach sample was then calculated and expressed as the amount of dry sandretained in g/m².

Two mats with identical tufted pile construction were subjected to thistest. The first mat was a tufted nylon cut pile conventional rubberbacked mat, which had been fabricated in an air bag press at 165° C. and30 psi. The mat was not washed prior to the test. The second mat was atufted nylon cut pile mat with a rubber crumb backing, which had alsobeen fabricated in an air bag press but at a lower temperature andpressure. The sand retention results were as follows:

Sample of prior art conventional rubber backed mat A: weightincrease=723 g/m²

Sample of inventive crumb rubber backed mat B: weight increase=2655 g/m²

Production of a conventional rubber backed mat significantly flattensthe pile on the mat. The lower temperature and pressure possible whenusing the same type of press (with a pressurised air bag and a heatedplaten) to produce a rubber crumb-backed, textile pile-faced mataccording to the invention results in a mat that does not suffersignificantly from pile crush. This gives a mat having, immediatelyafter manufacture, good dust control properties without being laundered.This good dust control performance is exemplified by a sand retentionvalue in excess of 2000 g/m² for the typical nylon tufted pile used inthis test. The sand retention performance for a mat according to theinvention is far superior to the sand retention performance of theconventional rubber-backed tufted nylon cut pile mat, prior to washing.The uncrushed pile also exhibits better “feel” by way of a moreluxurious texture.

The mats according to the invention exhibit superior fire resistance tothose made from conventional nitrile rubber backing of the samethickness. When tested according to BS4790, mats made from powdernitrile rubber crumb and granule nitrile rubber crumb showedsignificantly higher resistance to ignition when compared to a mat madefrom conventional nitrile rubber backing. This is recorded in Table 7.TABLE 7 Regular mat with solid Mat with crumb rubber backing granulebacking Time to extinguish (s) 170 50 Radius of effects top (mm) 50 25Radius of effects lower (mm) 50 25

This can be further improved by the addition of more binder and/oranti-flammability additives to the backing and is especially useful whenused in conjunction with a low flammability textile surface. Such a lowflammability textile surface may, for example, be one that ispredominantly a woollen construction.

When compared with PVC backed mats, the mats of the invention that have4 mm or larger crumb rubber in the backing have better resistance tomovement on carpets. On average, these mats according to the inventiondisplay significantly improved resistance to movement on carpetscompared with PVC backed mats.

A modified mat and a method of manufacturing the modified mat will nowbe described with reference to FIGS. 6 and 7. FIG. 6 is an exploded sideview of a laid-up mat assembly, prior to pressing, which includes abacking layer 18 comprising a mixture of rubber crumb and a binder, anda layer of fabric 20 that will form the textile layer 1 of the mat. Anedging strip 24 is located adjacent each edge of the backing layer 18,between the backing layer and the fabric layer 20. The fabric layeroverlaps the edging strip 24 by about 1-2 cm. The edging strip 24 may bemade for example of unvulcanised rubber, and may have a thickness oftypically 0.35-0.45 mm and a width of 2-5 cm.

FIG. 7 is an enlarged cross-sectional side elevation of the modifiedmat, showing an edge portion of the mat after completion of the pressingoperation. The rubber crumb/binder mixture has been consolidated to forma backing layer 2 and the fabric layer has been bonded to the backinglayer to form the textile layer 1 of the mat. The edging strip 24 isbonded to the upper face of the rubber crumb backing layer 2 and ispartially overlapped by and bonded to the textile layer 1.

The edging strip 24 hides the rubber crumb backing layer 2 so that theborder portion of the mat has the appearance of a conventional rubberbacked mat with a solid rubber backing. This may be desirable in certaincircumstances for aesthetic reasons. It also prevents dust and dirt fromcollecting in the small voids between the crumbs in the upper face ofthe rubber border to provide a cleaner appearance. In addition, theedging strip increases the tear strength of the mat border. This in turnallows a larger crumb size to be used, which reduces costs and providesincreased stability on carpeted surfaces.

Edging strips 24 may be provided on just the two longitudinal side edgesof the mat (particularly in the case of continuous matting), or on allfour edges of the mat. The strips 24 may be bonded to the backing layer2 and the textile layer 1 by vulcanisation during pressing, or by usinga glue or a thermoplastic adhesive. The strips 24 may be made of othermaterials, including for example thermoplastic materials. The strips mayalso be pre-applied to the fabric layer, prior to pressing, either byglue or vulcanisation. After pressing, any portion of the backing layerthat extends beyond the edging strip and, if necessary, the outer edgeof the edging strip 24 may be trimmed off to provide a flush edge.

Other mats can also be made according to the invention including, forexample, floor mats such as poster mats or foam sandwich mats, tablemats, drinks mats and bar runners.

1-28. (canceled)
 29. A mat, said mat comprising a textile surface and anelastomer backing, said elastomer backing including elastomer crumbs, abinder, and a plurality of voids between the elastomer crumbs, whereinthe backing has a density in the range 0.5 to 0.9 g/cm³, and wherein themat includes a rubber crumb border that extends beyond the periphery ofthe textile surface along at least two edges of the mat.
 30. A mataccording to claim 29, wherein the elastomer crumb is crumbed vulcanizedrubber.
 31. A mat according to claim 30, wherein the rubber is nitrilerubber.
 32. A mat according to claim 29, wherein the elastomer backinghas a bulk density less than the solid density of the elastomer crumbmaterial.
 33. A mat according to claim 32, wherein the elastomer backinghas a bulk density in the range of 45% to 70% of the solid density ofthe elastomer crumb material.
 34. A mat according to claim 33, whereinthe elastomer backing has a bulk density in the range of 55% to 70% ofthe solid density of elastomer crumb material.
 35. A mat according toclaim 29, wherein the backing has a density in the range 0.7 g/cm³ to0.9 g/cm³.
 36. A mat according to claim 29, characterized in that theelastomer backing exhibits a deformability, as measured by the testherein defined, of at least 14%.
 37. A mat according to claim 36,characterized in that the elastomer backing exhibits a deformability, asmeasured by the test herein defined, of between 14% and 50%.
 38. A mataccording to claim 29, wherein the elastomer backing exhibits a tearresistance strength of at least 8 N/mm².
 39. A mat according to claim29, wherein the backing has a thickness of at least 1 mm.
 40. A mataccording to claim 29, wherein the crumb size is less than 5 mmdiameter.
 41. A mat according to claim 40, wherein the crumb size issubstantially in the range of between 2 mm and 4 mm.
 42. A mat accordingto claim 29, wherein the elastomer crumb backing includes at least 10%by weight powdered elastomer crumb.
 43. A mat according to claim 29,wherein the binder is present at a level from 2% to 20%.
 44. A mataccording to claim 43, in which the elastomer crumb backing includesless than 1% by weight of powdered elastomer crumb and the binder ispresent at a level from 2 to 12%.
 45. A mat according to claim 43,wherein the elastomer crumb backing includes at least 10% by weight ofpowdered elastomer crumb and the binder level lies in the range 9 to10%, preferably about 14%.
 46. A mat according to claim 43, wherein thebinder is a polyurethane MDI binder.
 47. A mat according to claim 46,wherein the binder is selected from the group consisting of4,4-methylene di-p-phenylene isocyanate polyurethane one- andtwo-component adhesives.
 48. A mat according to claim 47, wherein thebinder is a solvent-free one-component polyurethane adhesive.
 49. A mataccording to claim 43, wherein the binder is a hot melt binder.
 50. Amat according to claim 29, wherein the backing includes powderedadditives selected from the group consisting of anti-microbialadditives, anti-flammability additives, pigments, and anti-staticadditives.
 51. The mat according to claim 29, wherein a crumb rubberborder extends around the entire periphery of the mat.
 52. A mataccording to claim 29, wherein the unwashed textile surface has a sandretention value of at least 1000 g/m².
 53. A mat according to claim 29,wherein the textile surface is selected from the group consisting of aknitted textile, a woven textile, a non-woven textile, and a flockedsubstrate.
 54. A mat according to claim 29, wherein an edging strip isbonded to the elastomer backing adjacent at least one edge thereof. 55.A mat according to claim 54, wherein the textile surface partiallyoverlaps and is bonded to the edging strip.
 56. A mat according to claim29, which is a floor mat.
 57. A mat according to claim 29, which is atable mat.
 58. A mat according to claim 29, which is a bar runner.